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time.c

/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include "linux/clockchips.h"
#include "linux/interrupt.h"
#include "linux/jiffies.h"
#include "linux/threads.h"
#include "asm/irq.h"
#include "asm/param.h"
#include "kern_util.h"
#include "os.h"

/*
 * Scheduler clock - returns current time in nanosec units.
 */
unsigned long long sched_clock(void)
{
      return (unsigned long long)jiffies_64 * (NSEC_PER_SEC / HZ);
}

void timer_handler(int sig, struct uml_pt_regs *regs)
{
      unsigned long flags;

      local_irq_save(flags);
      do_IRQ(TIMER_IRQ, regs);
      local_irq_restore(flags);
}

static void itimer_set_mode(enum clock_event_mode mode,
                      struct clock_event_device *evt)
{
      switch(mode) {
      case CLOCK_EVT_MODE_PERIODIC:
            set_interval();
            break;

      case CLOCK_EVT_MODE_SHUTDOWN:
      case CLOCK_EVT_MODE_UNUSED:
      case CLOCK_EVT_MODE_ONESHOT:
            disable_timer();
            break;

      case CLOCK_EVT_MODE_RESUME:
            break;
      }
}

static int itimer_next_event(unsigned long delta,
                       struct clock_event_device *evt)
{
      return timer_one_shot(delta + 1);
}

static struct clock_event_device itimer_clockevent = {
      .name       = "itimer",
      .rating           = 250,
      .cpumask    = CPU_MASK_ALL,
      .features   = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
      .set_mode   = itimer_set_mode,
      .set_next_event = itimer_next_event,
      .shift            = 32,
      .irq        = 0,
};

static irqreturn_t um_timer(int irq, void *dev)
{
      (*itimer_clockevent.event_handler)(&itimer_clockevent);

      return IRQ_HANDLED;
}

static cycle_t itimer_read(void)
{
      return os_nsecs();
}

static struct clocksource itimer_clocksource = {
      .name       = "itimer",
      .rating           = 300,
      .read       = itimer_read,
      .mask       = CLOCKSOURCE_MASK(64),
      .mult       = 1,
      .shift            = 0,
      .flags            = CLOCK_SOURCE_IS_CONTINUOUS,
};

static void __init setup_itimer(void)
{
      int err;

      err = request_irq(TIMER_IRQ, um_timer, IRQF_DISABLED, "timer", NULL);
      if (err != 0)
            printk(KERN_ERR "register_timer : request_irq failed - "
                   "errno = %d\n", -err);

      itimer_clockevent.mult = div_sc(HZ, NSEC_PER_SEC, 32);
      itimer_clockevent.max_delta_ns =
            clockevent_delta2ns(60 * HZ, &itimer_clockevent);
      itimer_clockevent.min_delta_ns =
            clockevent_delta2ns(1, &itimer_clockevent);
      err = clocksource_register(&itimer_clocksource);
      if (err) {
            printk(KERN_ERR "clocksource_register returned %d\n", err);
            return;
      }
      clockevents_register_device(&itimer_clockevent);
}

extern void (*late_time_init)(void);

void __init time_init(void)
{
      long long nsecs;

      timer_init();

      nsecs = os_nsecs();
      set_normalized_timespec(&wall_to_monotonic, -nsecs / NSEC_PER_SEC,
                        -nsecs % NSEC_PER_SEC);
      set_normalized_timespec(&xtime, nsecs / NSEC_PER_SEC,
                        nsecs % NSEC_PER_SEC);
      late_time_init = setup_itimer;
}

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